Process for the hydrogenolysis of light hydrocarbons



we? a j United States Patent 0 3,180,902 PRCCESS FOR THEHYDROGENOLYSiIiS GF LIGHT HYDRGCARBONS Holger C. Andersen, Morristown,and Philip L. Romeo, 01d Bridge, NJ, assignors to Engeihard Industries,inc, Newark, NJ a corporation of Delaware No Drawing. Filed Aug. 10,1961, Ser. No. 130,478 2 Claims. (Cl. 260-676) In accordance with thepresent invention, a novel and meritorious process is provided for thehydrogenolysis of non-cyclic, aliphatic light saturated and/orunsaturated hydrocarbons characterized by having 2-7 carbon atoms permolecule, to produce methane. In its broader aspects, the processinvolves passing an admixture of hydrogen and the light hydrocarbon intocontact with a platinum group metal catalyst, preferably a supportedcatalyst, at an elevated temperature, preferably from about 80 C.600 C.By reason of such catalytic contacting at a temperature within the rangespecified, hydrogenolysis of the light hydrocarbon molecules is effectedand the methane is produced. The process is of merit because achievingthe following advantages: (1) eifects hydrogenolysis of the lighthydrocarbons cfiici'ently and with relative ease, cracking of lighthydrocarbons heretofore being attended with relative difiiculty; and (2)produces a methane-containing product gas which is a good fuel gas andinterchangeable with natural gas and other fuel gas.

Natural gas, which consists mainly of CH is frequently used as a fuelfor reasons of economy and convenience, and fuel burners using naturalgas are adjusted for the proper intake of fuel and air. It has been oneof the major problems of the utility gas industry to develop processesfor peak-load substitutes for natural gas. Where a low molecular weightfeed is available, this invention is eminently adapted for theproduction of CH It is also noteworthy that one of the major problems indeveloping a substitute for natural gas is the reduction of unsaturatedhydrocarbons, since combustion of unsaturated hydro-carbons results inyellow-tipping and soot deposition. It has been difiicult to reduce theunsaturated hydrocarbons to CH i.e. it could be accomplished only athigh temperatures with resultant high rates of carbon formation.According to this invention the unsaturated hydrocarbons react with H toform CH at relatively low temperatures.

The attainment of hydrogenolysis of the light hydrocarbons of thisinvention with relative case was unexpected and surprising, inasmuch asheretofore cracking of such light hydrocarbons was difficult as comparedwith cracking of higher molecular weight hydrocarbons containing morethan 7 carbons per molecule.v The hydrogenolysis of hydrocarbons havingfrom 2-4 carbon atoms Patented Apr. 27, 1965 .per molecule with ease inaccordance with this invention was deemed to be especially anachievement.

The platinum group metals which are employed as catalysts in the presentinvention are preferably carried on a suitable support, for instanceactivated alumina, carbon, silica gel and di-atomaceous earth, and anycombination thereof. The platinum group metal is preferably rhodium,ruthenium, palladium, platinum and combinations of such metals, forinstance ruthenium and platinum, ruthenium and palladium, and rhodiumand platinum. The catalyst metal is preferably present in amount ofabout 0.1 -5 weight percent, more preferably about 0.32 weight percentof the catalyst metal and support. The extent of the crackingv-arieswith the particular catalyst used, the support, and the concentration ofcatalyst.

Temperatures of from about 0-600 C. are preferred in the presentinvention inasmuch as temperatures much above 600 C. tend to result ingreater coke formation. Temperature-s much below 80 C. should beavoided, as the hydrogenolys-is will not be affected to any appreciableextent at such temperatures. The optimum temperature employed dependsupon the nature and concentration of the catalyst as well as the natureand concentration of the reactants. More preferably, for thehydrogenolysis of ethane-containing gas, temperatures between 200 C. and300 C. are employed when utilizing arhodium catalyst, between C. and 400C. when using a ruthenium catalyst, between 300 C. and 400 C. whenemploying a palladium catalyst, between 210 C. and 300 C. when employinga ruthenium-platinum catalyst, and between 220 C. and 450 C. whenutilizing a ruthenium-palladium catalyst.

Hydrocarbons which are subjected to the hydrogenolysi-s of the presentinvention are non-cyclic aliphatic light hydrocarbons which may besaturated and/or unsaturated, and substituted and/or unsubstituted. Thenumber of carbon atoms per molecule of the hydrocarbon can range from2-7. Examples of such hydrocarbons include ethane, ethylene, propane,propylene, butane, 1- .butene, hexane, n-hexylene, pentane, l-pentene,heptane, heptylene, and 2,2-dimethyl butane.

The proportion of hydrogen in the. input mixture can be varied and theextent of the hydrogenolysis depends on the ratio of hydrocarbon tohydrogen in the input mixture. For greatest percentage yield of methanea quantity of hydrogen is utilized which is that stoic-hi0- metricallyrequired for reaction with all the hydrocarbon to produce methane.Exemplary hydrogenolysis reactions of this inventionutilizing ethane ashydrocarbon in reaction (1) and pentane as hydrocarbonin reaction (2)are set forth below: i

adsorption, it is frequently possible to regenerate the catalyst byburning offthe coke and/or sulfur by treatment with oxygen-containinggas.

Space velocities employed can range up to 20,000 standard volumes of gasper volume of catalyst per hour, preferably from about 1000 to 10,000standard volumes arrests anemone gas per volume of catalyst per hour.The reaction will proceed at pressures ranging from about 0-1000p.s.i.g. The invention will be further illustrated by reference to thefollowing examples.

EXAMPLE I A mixture of 55 mol percent ethane and 45 mol percent hydrogenwas metered through a rotameter into a reactor of 1" diameter containing20 ml. of 0.5 percent Ru on activated A1 0 pellets at a temperature ofabout 220 C. The resultant gaseous products were analyzed by an infraredspectrophotometer and 85 mol percent methane was noted.

Other mixtures of hydrocarbon and hydrogen gases set forth in Table I,were similarly tested for hydrogenolysis with the ruthenium catalyst.

Results of these experiments are listed in Table I.

Table I The data in Table I show that a ruthenium catalyst in thepresence of hydrogen promoted the cracking of light, aliphatic,saturated hydrocarbons to form methane.

In tabulating the data in Table I, minor ingredients in inlet and outletgases are omitted to simplify interpretation of the data. Apparentdiscrepancies in the determination of yields and in the analysis oftotal product gases present are within the limits of experimental andanalytical error with the methods used.

EXAMPLE II Using the procedure described in Example I, gas mixturesranging from 5 mol percent ethane and 95 mol percent hydrogen to 99 molpercent ethane, 0.15 mol percent methane, 0.85 mol percent ethylene andno hydrogen were employed to determine the yield of methane at varioustemperatures.

CATALYTIC HYDRO GENOLYSIS OF HYDROCARBONS Catalyst: m1. of 0.5% Ru on Wactivated A1 0 pellets Pressure: 0 p.s.i.g. Space velocity: 2000-3000s.c.f.h./c.i.

EFFECT OF CATALYST ON ETHANE-HYDROGEN MIX- TURES Catalyst: 0.5% Ru on 5activated A1 0 pellets Conditions:

Pressure-O p.s.i.g.

Space vel0city2000-3000 s.c.f.h./c.i.

Inlet, mol percent 1 Outlet, mol percent Cale. temp.

for 100% yield of 1 Small amounts of C 11 present as impurities.

2 Not analyzed.

3 Inlet mixture includes 0.9 mol percent C 114, 0.72 mol percent 00outlet mixture includes 0.40 mol percent CgH4, trace of CO; 1.0 molpercent CO.

From the data in Table II it is evident that in the hydrogenolysis ofethane, where the catalyst and other conditions are constant, the extentof the hydrogenolysis varies with the temperature and the concentrationsof ethane and hydrogen in the input mixture.

It is also evident from Table II that the Ru catalyst in the presence ofH promoted the cracking of ethane in a 82 mol percent ethane-l8 molpercent hydrogen input mixture, approaching maximum yield at atemperature of approximately C., while no appreciable cracking occurredin ethane (99 percent) through 383 C. in the absence of hydrogen.

EXAMPLE III Using the procedure described in Example I, a mixture of 41mol percent C H and 49 mol percent hydrogen was metered into a reactorcontaining 10 ml. of 0.5 percent Ru on A3" activated A1 0 pellets.Similarly, mixtures of approximately the same proportions of gases weremetered into other reactors containing other catalysts as listed inTable III.

Table III EFFECT OF CATALYSTS IN PROMOTING THE HYDROGENOLYSIS OF ETHANE[Amount of eata1yst-10ml.; space v'eloclty-4000 s.0.f.h./c.f.;pressurep.s.i.g.]

Inlet mol percent 1 Outlet mol percent Catalyst Tgrgp V 00 H, CH4 0,11,can, o0 H, 01-1., 0 H; one,

0.5% Ru on 14' activated A1201 pellets 174 0.48 49 14 1.5 41 06 17 47.03 I 27 0.5% Rh on 16" activated A1203 pellets 210 0. 36 49 14 1. 7 410060 "0. 6 84 02 002 0.5% Pd on ,4 activated A1203 pellets. 360 0. a6 4914 1.6 41 0005 20 40 02 32 400 0.36 49 14 1. a 41 0005 30 28 02 38 I420. 0.36 40 14 1.6 41 0005 44 19 02 44 1% Pt on carbon 460 0.36 4914 1. 6 41 0. 34 86 30 02 34 0.3% Pt'+0.2% Ru on z activated 1 A1 03pellets 210 0 36 49 14 1 7 41 0060 6.6 79 02 10 0.4% Pd+0.1% Ru on 942'activated A1 0 pellets 240 0. 40 49 14 1. 6 41 0005 6. 0 75 02 11 490 0.40 49 14 1. 6 41 50 4s 0. 69 45 5% Co on 14' A1 0; spheres 280-350 0. 3e49 14 1. 6 41 0.26 45 14 03 42 Hopcalite (Ag-Mn) 160 0. 36 49 14 1. 3 420. 34 4s 15 1. 2 42 450 0. 36 40 14 1. 3 42 0. 36 4s 14 0. 40 43 Finelydivided copper 370 0. 30 49 14 1.6 42- 0.28 47 14 .02 43 425 0. 36 4914 1. 6 42 0. 24 47 14 02 43 1 Inlet mixture includes 0.07 mol percent02. 2 Not analyzed. I 5

The results tabulated in Table III indicate that the ease v 01hydrogenolysis of ethane varies with the catalyst. Fur- EXAMPLE Vthcrmore, it is evident that ruthenium and rhodium are particularlyeffective in promoting this reaction at relatively low temperatures,and, ruthenium in combination with platinum, and ruthenium incombination with palladium are effective catalysts.

EXAMPLE IV Using the procedure described in Example I, mixtures ofethane and hydrogen were passed over 10 n11. of Pd catalyst. Asindicated in Table IV, the metal content of catalyst was varied.

Table IV The following experiments are set forth to show the promotionof hydrogenolysis of an unsaturated and of a branched, aliphatic lighthydrocarbon to form methane by a platinum group metal catalyst in thepresence of hydrogen. The experiments were conducted at 0 p.s.i.g.

Using the procedure described in Example I, approximately 41 mol percentC l-I 14 mol percent CH 1.5 mol percent C H 0.48 mol percent CO, 0.07mol percent 0 and the balance H was metered through a rotameter into areactor containing 10 ml. of 0.5 percent Ru on activated A1 0 pellets.The space velocity EFFECT OF VARIATION OF CATALYST METAL CONTENT ONHYDROGENOLYSIS OF ETHANE Catalyst-1O ml. Conditions:

Pressure0 p.s.i.g.

1 Inlet mixture includes 0.07 mol percent 02. B N 01; analyzed The datain Table IV indicate that the ease of hydrogenolysis increases with themetal content of catalyst used.

The general comments in Example I regarding reported data apply also toTables 11, Ill and IV.

Inlet mol percent 1 Outlet mol percent Catalyst Tgrgp,

' 00 H; CH4 CzH 02116 CO H; CH C2114 C 11 0.5% Pd on $6 activated A1203pellets- 360 0.36 49 14 1. G 41 0005 40 02 32 400 0.36 49 14 1. 6 410005 28 02 38 420 0.36 49 14 1. 6 41 0005 44 19 02 44 2% Pd on activatedA1 0 pellets" 300-390 0.36 49 14 1. 6 41 0. 13 2 0 85 02 0020 0.4%Pd+0.1% Ru on 042" activated A1201 240 0.40 49 14 1. 6 41 0005 6 0 75 0211 pellets. 490 0. 49 14 1. 6 41 0.50 48 15 0 69 was 4000 s.c.f.h./c.f.The resultant gaseous products at various temperatures were analyzed byan infrared specpassed through a micro-bubbler filled with neohexane andover 20 ml. of Ru on A3 activated A1 0 pellets. The space velocity was4750 s.c.f.h./c.f. The inlet mixture contained 45.5 mol percentneohexane and 54.5 mol percent H A gas sampling bulb in series with acold trap was used to collect the samples for analysis. Analysis of theetlluent gases showed that 4.0 mol percent CH was formed at 90 C. andconsiderable quantities of CH, were formed at higher temperatures.Infrared analysis of the outlet mixtures, with temperatures ranging to432 C., did not show the formation of reaction products other than CH Noattempt was made to determine exact quantities, but considerablequantities of CH, were formed at temperatures below 200 C.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and this invention includes all suchmodifications.

What is claimed is:

1. A process for the hydrogenolysis of non-cyclic aliphatic lighthydrocarbons which comprises passing a gaseous admixture of hydrogen anda gas containing primarily a hydrocarbon from the group consisting ofnoncyclic saturated aliphatic light hydrocarbons having from 2-4 carbonatoms per molecule, ethylene, propylene,

l-butene, and mixtures of the saturated and olefin hydrocarbonsaforesaid, into contact with a supported catalyst consisting essentiallyof a catalytic metal selected from the group consisting of ruthenium anda rutheniumpalladiurn combination, supported on activated alumina, at atemperature within the range of between 197 C. and 370 C. and a spacevelocity from about 1000 to 10,000 standard volumes of gas per volume ofcatalyst per hour, the catalytic metal being present in amount of about0.1-5 weight percent based on catalytic metal plus sup port, wherebyhydrogenolysis of the hydrocarbon occurs to produce gaseous reactionproducts comprising methane.

2. A process in accordance with claim 1 wherein the gas admixed with thehydrogen contains primarily ethane.

References Cited by the Examiner UNITED STATES PATENTS 2,854,401 9/58Weisz 208112 2,909,578 10/59 Anderson et a1 26067 7 2,964,462 12/60Thomas et a1. 208-112 3,000,809 9/61 Ridgway et a1. 260676 3,046,3177/62 Myers 260676 3,048,536 8/62 Coonradt et al 208l 12 OTHER REFERENCESBeeck: Faraday Society--Discussions, 1950, No. 8, pages 118-128.

ALPHONSO D. SULLIVAN, Primary Examiner.

DANIEL E. WYMAN, Examiner.

1. A PROCESS FOR THE HYDROGENEOLYSIS OF NON-CYCLIC ALIPHATIC LIGHTHYDROCARBONS WHICH COMPRISES PASSING A GASEOUS ADMIXTURE OF HYDROGEN ANDA GAS CONTAINING PRIMARILY A HYDROCARBON FROM THE GROUP CONSISTING OFNONCYCLIC SATURATED ALIPHATIC LIGHT HYDROCARBONS HAVING FROM 2-4 CARBONATOMS PER MOLECULE, ETHYLENE, PROPYLENE, 1-BUTENE, AND MIXTURES OF THESATURATED AND OLEFIN HYDROCARBONS AFORESAID, INTO CONTACT WITH ASUPPORTED CATALYST CONSISTING ESSENTIALLY OF A CATALYTIC METAL SELECTEDFROM THE GROUP CONSISTING OF RUTHENIUM AND A RUTHENIUMPALLADIUMCOMBINATION, SUPPORTED ON ACTIVATED ALUMINA, AT A TEMPERATURE WITHIN THERANGE OF BETWEEN 197*C. AND 370*C. AND A SPACE VELOCITY FROM ABOUT 1000TO 10,000 STANDARD VOLUMES OF GAS PER VOLUME OF CATALYST PER HOUR, THECATALYTIC METAL BEING PRESENT IN AMOUNT OF ABOUT 0.1-5 WEIGHT PERCENTBASED ON CATALYTIC METAL PLUS SUPPORT, WHEREBY HYDROGENOLYSIS OF THEHYDROCARBON OCCURS TO PRODUCE GASEOUS REACTION PRODUCTS COMPRISINGMETHANE.